From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1792706606; b=lczgAYdwn7dUCe+o0S6225G2UROT/FcGya0HvNa1ef/+AhS8JNraZglV5QYirY0XqssK s8yPNzKO5s0H69e/hyQyfK6DClhEPL8Kn9kq2R0mgYWIQEOcLo8jwQtl16vj/xGThLH9u fDcy+5DNgm8/MIKwGLWmX0HaZUwN736dprQvCxE0q9vadodKS9ZKEUW3M/r7DznISh1hx 5CIRLhdHJNIx+MC6O0TX5CVrxS1pmqyKcid1gBBzMbnNE/FJUPr086dSLmfiTCsWAt9yR QQ5SZ8uLEu6zkNSpkpLkuKKjt+xESw+eeJXdbt1tDqvR9JRKENhHrEXsqorQSdBVXNQ== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1792706606; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-Id:X-Mailer: In-Reply-To:References:MIME-Version:Content-Transfer-Encoding; bh=x5g4D3hEwc7GK+nQos56fFKgAhNh3H0jKC5fCgXobkg=; b=bdiRReQ3avIJP0YtVLsvawp08I/CsQiOSjlbRKhdkAEk7DUF04ZdfcD6BsF2e6mW3zOG PQ1OD0SxMPlz4bklD2QIiE+qlfXuj3nuJC3heM8IM+KGG1SLryp+VrSw5K70+wYClY3Iz sIDs88eeR/ILi9p30VHF0aDC8fng6Xv0WHeVGS95gA7SHAwP33JI/5a7S9mFC769CwtT3 X0NLVOreYn7hj4wb1HtFELBmbaze8Jcmk8CUIAlTpNRzHm0+p8gTrKdG2x54ljqX+l4NI efDcBrFKYTNKOru4jWxIjAsMX0ajztvVLOdw+j9y1J9tsuVvYZDDkBhn3MYpDYXMugA== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=DpnLxfxC; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8966B606A31B for ; Thu, 22 Oct 2026 22:03:26 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=DpnLxfxC Received: by smtp.kernel.org (Postfix) with ESMTPSA id 85C181F01829; Thu, 22 Oct 2026 22:03:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1792706606; bh=x5g4D3hEwc7GK+nQos56fFKgAhNh3H0jKC5fCgXobkg=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=DpnLxfxCgxMDb32Z2c8mEShELG4hi0o4Yo00Cxrxh1xB7RIknx6C7gC8fgtZGN6HI KMkbyw2c9MEhy/qdoVTDrc9QY9hsMNeKvCT/iGbL0YvyZzVX/rPdb1ClNy614kxCFL TDvTU0rnJk+8yotIbkKZH8kawmZT+PNUwzWU7rGfng7QGLnJYxGlx4XKA0CHT99bGm uhPDuyT6deMTTrsAlAyyLkcqY4xZmd555jRLS9FxPQL3DXl4662uIkLTkOoomN5/rQ Wo8wxH3JYEHotpZXhLcFx28w7f8IHGOE0pWalAmLDJSeeZK4sOx6U1hVjs3IPTh0ps dUe00IyGnD+aA== From: "Barry Song (Xiaomi)" To: akpm@linux-foundation.org, linux-mm@kvack.org Cc: hui.zhu@linux.dev, axelrasmussen@google.com, baohua@kernel.org, baolin.wang@linux.alibaba.com, david@kernel.org, hannes@cmpxchg.org, linux-kernel@vger.kernel.org, ljs@kernel.org, mhocko@kernel.org, qi.zheng@linux.dev, ryncsn@gmail.com, shakeel.butt@linux.dev, weixugc@google.com, yuanchu@google.com, zhuhui@kylinos.cn, baoquan.he@linux.dev, liuxiang.277@bytedance.com, wangzicheng@honor.com, lianux.mm@gmail.com, kasong@tencent.com, liam@infradead.org, surenb@google.com, mhocko@suse.com, rppt@kernel.org, zhangbo56@xiaomi.com, lyugaofei@xiaomi.com, ridong.chen@linux.dev, kunwu.chan@gmail.com Subject: [RFC PATCH v5 14/14] mm/mglru: Avoid scan anon while swapcache is low for GFP_NOIO allocation Date: Fri, 23 Oct 2026 06:02:03 +0800 Message-Id: <20261022220203.91911-15-baohua@kernel.org> X-Mailer: git-send-email 2.39.3 (Apple Git-146) In-Reply-To: <20261022220203.91911-1-baohua@kernel.org> References: <20261022220203.91911-1-baohua@kernel.org> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Bo Zhang With GFP_NOIO, we cannot reclaim anon folios unless they are in the swap cache. CLRU skips anon reclaim when the swap cache is very low by commit 74d9aa0d8e98 ("mm: vmscan: avoid anon scanning for GFP_NOIO with low swapcache"). Apply the same logic to MGLRU. The new scan-budget-based mechanism makes this straightforward to implement. Thanks also to Xiang Liu, who previously attempted to fix this before we had the scan-budget-based model [1]. [1] https://lore.kernel.org/linux-mm/179248830836.1744016.8424217811286616919.noio-mglru-rfc-v2@bytedance.com/ Cc: Xiang Liu Signed-off-by: Bo Zhang Co-developed-by: Barry Song (Xiaomi) Signed-off-by: Barry Song (Xiaomi) --- mm/vmscan.c | 20 ++++++-------------- 1 file changed, 6 insertions(+), 14 deletions(-) diff --git a/mm/vmscan.c b/mm/vmscan.c index 6d5a823667e0..d72a5aef3a0f 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -379,13 +379,6 @@ static inline bool reclaimable_anon_is_low(struct mem_cgroup *memcg, if (!sc || (sc->gfp_mask & __GFP_IO)) return false; - /* - * FIXME: MGLRU doesn't fully respect can_reclaim_anon_pages() for the - * scanning type, so only apply this to the traditional LRU for now. - */ - if (lru_gen_enabled()) - return false; - if (memcg) { struct lruvec *lruvec = mem_cgroup_lruvec(memcg, pgdat); @@ -5061,26 +5054,23 @@ static void lru_gen_balance_scan(struct lruvec *lruvec, struct scan_control *sc, { struct lru_gen_folio *lrugen = &lruvec->lrugen; u64 refault_rate[ANON_AND_FILE], anon_factor, file_factor; - u64 anon_scan, file_scan, total; + u64 anon_scan, file_scan; u64 anon_weight, file_weight; int size_bias; - total = nr[LRU_GEN_ANON] + nr[LRU_GEN_FILE]; - if (!total) - return; - if (swappiness <= MIN_SWAPPINESS) { nr[LRU_GEN_ANON] = 0; nr[LRU_GEN_FILE] = min_t(u64, total_scan, nr[LRU_GEN_FILE]); - return; } if (swappiness == SWAPPINESS_ANON_ONLY) { nr[LRU_GEN_FILE] = 0; nr[LRU_GEN_ANON] = min_t(u64, total_scan, nr[LRU_GEN_ANON]); - return; } + if (!nr[LRU_GEN_ANON] || !nr[LRU_GEN_FILE]) + return; + for (int type = LRU_GEN_ANON; type <= LRU_GEN_FILE; type++) { int hist = lru_hist_from_seq(READ_ONCE(lrugen->min_seq[type])); /* start at MIN_LRU_BATCH to smooth the rate on gen start */ @@ -5306,6 +5296,8 @@ static void lru_gen_prepare_scan(struct lruvec *lruvec, struct scan_control *sc, unsigned long total; lruvec_evictable_size(lruvec, swappiness, nr_to_scan); + if (!can_reclaim_anon_pages(memcg, lruvec_pgdat(lruvec)->node_id, sc)) + nr_to_scan[LRU_GEN_ANON] = 0; total = nr_to_scan[LRU_GEN_ANON] + nr_to_scan[LRU_GEN_FILE]; /* Just scrape all pages calculated above if this memcg was deleted */ -- 2.34.1